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Hubble Space Telescope Observations of Field Ultracool Dwarfs at High Galactic Latitude

Ryan, R. E., Jr. and Thorman, P. A. and Yan, H. and Fan, X. and Mechtley, M. R. and Hathi, N. P. and Cohen, S. H. and Windhorst, R. A. and McCarthy, P. J. and Wittman, D. M. (2011) Hubble Space Telescope Observations of Field Ultracool Dwarfs at High Galactic Latitude. Astrophysical Journal, 739 (2). Art. No. 83. ISSN 0004-637X. https://resolver.caltech.edu/CaltechAUTHORS:20111012-075444341

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Abstract

We present a sample of 17 newly discovered ultracool dwarf candidates later than ~M8, drawn from 231.90 arcmin^2 of Hubble Space Telescope Wide Field Camera 3 infrared imaging. By comparing the observed number counts for 17.5 ≤ J_(125) ≤ 25.5 AB mag to an exponential disk model, we estimate a vertical scale height of z_(scl) = 290 ± 25 (random) ± 31 (systematic) pc for a binarity fraction of f_b = 0. While our estimate is roughly consistent with published results, we suggest that the differences can be attributed to sample properties, with the present sample containing far more substellar objects than previous work. We predict the object counts should peak at J_(125) ~ 24 AB mag due to the exponentially declining number density at the edge of the disk. We conclude by arguing that trend in scale height with spectral type may breakdown for brown dwarfs since they do not settle onto the main sequence.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/0004-637X/739/2/83DOIArticle
http://iopscience.iop.org/0004-637X/739/2/83PublisherArticle
Additional Information:© 2011 The American Astronomical Society. Received 2011 May 4; accepted 2011 July 14; published 2011 September 12. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. We thank the anonymous referee and Adam Burgasser for many insightful and helpful comments and suggestions. Support for this work was provided by NASA through grant numbers 11772 (for R.E.R), 11702 (for H.Y and M.R.M), and 11359 (for S.H.C) from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555. R.A.W. acknowledges support from NASA JWST Interdisciplinary Scientist grant NAG5-12469 from GSFC. Facility: HST (WFC3)
Funders:
Funding AgencyGrant Number
NASA11772
NASA11702
NASA11359
NASANAS 5-26555
NASANAG5-12469
Subject Keywords:brown dwarfs; Galaxy: stellar content; Galaxy: structure; stars: low-mass
Issue or Number:2
Classification Code:PACS: 97.20.Vs; 97.10.Me; 98.35.Ac; 97.10.Tk; 98.35.Ce; 98.35.Bd
Record Number:CaltechAUTHORS:20111012-075444341
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20111012-075444341
Official Citation:Hubble Space Telescope Observations of Field Ultracool Dwarfs at High Galactic Latitude R. E. Ryan, Jr. et al. 2011 ApJ 739 83
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:27175
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:12 Oct 2011 15:21
Last Modified:03 Oct 2019 03:21

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